Railway signaling system



Nov. 3, 1942.

G. R. PFLASTERER RAILWAY SIGNALING SYSTEM Filed Dec. 10, 1941 3 Sheets-Sheet 1 a Q" a & x

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"a s ss- 1 R 0 A A A V 9 [NVEWTGH Gig P579 P/ZUSZQPQP HIS Arman/E1 Nov. 3, 1942. G. R. PFLASTERER RAILWAY SIGNALING SYSTEM Filed Dec, 10, 1941 3 Sheets-Sheet 3 [NVENIOIZ George flasze ep HIS ATTORNE'Y Patented Nov. 31, 1942 omen STATES'PATENT OFFICE.

RAILWAY SIGNALING SYSTEM George R. Pflasterer, Greenville, Pa., assignor to The Union Switch and Signal Company, Swissvale, Pa, a corporation of Pennsylvania Application December 10, 1941, Serial No. 422,309

3 Claims.

My invention relates to a railway signaling system of a type adapted for use on stretches of single track over which traffic moves in both directions, and particularly to a three block, four indication absolute permissive signaling system arranged to provide a double caution indication when trains moving in opposite directions approach a passing siding.

It is an object of this invention to provide an improved signaling system of the type described in which alternating current is employed concurrently with direct current of one polarity or the other in the system line circuits to thereby provide the desired number of difierent signal indications with a minimum of line wires.

ther objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings.

I shall describe one form of railway signaling system embodying my invention and shall then point out the novel features thereof in claims.

In the drawings Figs. 1A, 1B and 1C, when placed together in the order named with Fig. 1A at the left constitute a diagram showing apparatus embodying one form of my invention applied to that portion of a single track railroad located between and including the ends of two adjacent passing sidings, while. when the drawings are placed together with Fig. 1A at the right of Fig. 10, they form a diagram showing the apparatus of my invention applied to the double track portion of the railroad which includes the siding situated between two adjacent single track stretches.

In order to simplify the drawings and to enable the circuits to be more readily traced I have identified each signal by a letter and number, and each relay by a letter or a combination of letters with a distinguishing prefix identifying the signal with which the relay is associated.

Furthermore, instead of showing the sources of current for energizing the various line and local circuits and the wires leading thereto in detail, I have shown only the terminals of these sources. The terminals of the sources of direct current are designated B and C, while the terminals of the source of alternating current are designated BX and OK. The direct current may be provided by batteries, while the alternating current may be supplied from a commercial source of power and distributed. throughout the track stretch by a transmission line, not shown.

Referring to the drawings, the reference characters l and la designate the track rails ofthe main track of a single track. stretch over which trafiic may move in either direction.

For purposes of illustration it will be assumed that the left-hand end of the track stretch is West, and that the right-hand end of the stretch is east so that train movements from left to right are eastbound, and train movementsfrom right to left are westbound. The track rails are divided by insulated joints 2 into track sections designated T with a distinguishing prefix. Each section is provided with a track circuit comprising the usual track battery connected across one end of the section rails and a track relay designated TR with an appropriate prefix, connected across the other end of the section rails.

The ends of the non-track circuited passing sidings PS are connected with the main track by track switches W. The switches W may be moved between their two positions by any appropriate means.

The headblock signaliS governs traffic on the main track moving from left to right across the switch 2W at the right-hand end of the passing siding into the adjacent single track stretch, while the headblock signal 58' governs traific on the main track moving from right to left across the switch 5W at the left-hand end of the passing siding into the adjacent single track stretch The spacing of trains moving in the same direction through the single track stretch is governed by signals t3 and 63, or by signals :38 and type, and each has an upperportion including a green or clear lamp G, a yellow lamp Y, and a red or stop lamp R, while each signal has a lower portion consisting of a yellow lamp' Y, which ashereinafter explained cooperates with the yellow lamp of the upper portion of the signal to provide a yellow lamp over a yellow lamp to give the approach medium indication.

In addition, the signals IS and 65 at the entrance ends of the passing sidings PS may have other portions, not shown, togovern movement of trains into the sidings.

The signals associated with the switches may be governed in accordance with th'e'position of the switches in the manner well known in the art. This control of the signals by the switches is not a part of this invention and has been omitted to simplify the disclosure;

Each signal has associated therewith a polarized relay H, which is preferably of the retained neutral type, and a relay J which is energized by current supplied through a transformer N and a rectifier, which cooperate as hereinafter explained to control the associated signal and to also control the supply of energy to the line circuit leading to the adjacent signal in the rear.

The intermediate signals 33 and 48 also have associated therewith directional stick relays SR.

The windings of the relays H are of such high impedance as to substantially prevent flow of alternating current therein, while the primary windings of the transformers N are of such high resistance as to substantially prevent flow of direct current therein.

The relays H and J are energized by current supplied over line circuits whichextend between adjacent signals. As shown, these circuits include a wire Ill which is common to the circuits for controlling the signals for both directions of trafiic, and wires designated E and W with appropriate prefixes which cooperate with the common wire ID to form circuits over which energy is supplied to govern the eastbound and westbound signals respectively.

In most instances the relay contacts are shown directly under the relay with which they are associated, but in some cases in order to simplify the drawings relay contacts are shown separated from the associated relay, and where this is done the relay with which the contacts are associated is indicated by appropriate reference characters placed directly above the contacts.

The equipment is shown in the condition which it assumes when the track stretch is vacant. As

the track stretch is vacant, the contacts of the track relays of the various track sections are picked up so that the line circuits are complete.

At this time direct current energy of normal polarity is supplied, by means hereinafter described, to the relay 6H over the line circuit comprising wire it! and wire 613 so that the neutral contact [2 of this relay is picked up and its polar contact [4 is in its normal position and energy is supplied to the green lamp G of signal (is. Alternating current is also supplied to this line circuit at this time so that energy is supplied through the transformer 6N and the associated rectifier to relay BJ and its contact I5 cooperates with neutral contact IS of relay SE to establish the circuit to supply alternating current energy to the primary winding of the transforn'ier 6M. The secondary winding of this transformer is included in series with line wire 4E so that alternating current is supplied over the line wires 4E and to the relay 4J.

In addition, contact l8 of relay 6J connects wire ID to terminal C of a local source of direct current, and contact [9 of the relay connects wire 4E to terminal B of the source so that direct current of normal polarity is supplied over the wires 4E and Ill to the relay 4H. Accordingly, neutral contact and polar contact 22 of relay 4H establish the circuit of the green lamp G of signal 48, and contact 23 of relay 4H establishes the circuit to supply energy to the primary winding of the transformer AM so that alternating current is supplied to the circuit consisting of wires 2E and I0.

Relay lJ is energized, as explained above, and its contact 25 connects wire IEI to terminal C of a source, and its contact 26 connects wire 2E to terminal B of a source of direct current so that direct current of normal polarity is supplied over the line wires Ill and 2E to rela 2H and its contacts 28 and 29 establish the circuit of the green or clear lampG of signal 2S, while its contact 35 train in section 6T.

establishes the circuit of the primary winding of transformer 2M so that alternating current is supplied to the line circuit formed by wires 6E and [0.

In addition, the contacts of relay lZJ are picked up so that its contact 32 connects wire ID to terminal C and its contact 33 cooperates with front contact 34 of relay ZTR to connect wire SE to terminal B of a source of direct current. Accordingly, direct current of normal polarity together with alternating current is supplied to the wires 6E and I0 and this energy may be supplied to equipment similar to that associated with signal 68.

Energy is supplied in a similar manner to the circuits for supplying energy to govern the Westbound signals. As hereinafter explained, direct current of normal polarity together with alternating current is supplied to the circuit consisting of Wires IW and [0. Accordingly, contacts 35 and 36 of relay l H establish the circuit of the green lamp G of signal IS, While contact 31 of relay IJ and contact 38 of relay lI-I establish the circuit of the primary winding of transformer IM so that alternating current is supplied over the circuit formed by line wires l0 and 3W to relay 3J.

In addition, contact 39 of relay lJ connects wire ID to terminal C and contact 40 connects wire 3W to terminal B so that direct current of normal polarity is supplied over line wires I ll and 3W to relay 3H and contacts 43 and 44 of this relay establish the circuit of the green lamp G of signal 38, while its contact 45 establishes the circuit to supply energy to the primary winding of the transformer 3M.

The contacts of 'relay 3J are picked up and its contact 48 connects wire ID to terminal C and its contact 49 connects wire 5W to terminal B so that direct current of normal polarity is supplied to the circuit formed by wires 5W and Ill. Accordingly, relays 5H and 5J are energized and contacts 52 and 53 of relay 5H establish the circuit of the green lamp G of signal 58, while contact 54 of relay 5H establishes the circuit of the primary winding of transformer 5M. As the contacts of relay 5J are picked up, its contact 56 connects wire I 0 to terminal C and its contact 51 cooperates with front contact 58 of track relay 5TB to connect wire lW to terminal B. Direct current of normal polarity together with alternating current is supplied to the circuit of wires l0 and IW and may be supplied to relays corresponding to those associated with signal I S.

From the foregoing it will be seen that when the track stretch is vacant, direct current of normal polarity together with alternating current is supplied to each line circuit with the result that each signal displays its green or clear indication, while alternating and direct current are supplied to the line circuit in the rear of the signal.

Operation of equipment on movement of an eastbound train through the track stretch When a train is present in section 6T at the left-hand or west end of the track stretch shown in the drawings, track relay GTR is released (see Fig. 1C) and interrupts line wires I0 and IW to thereby prevent the supply of energy to the relays IJ and IH. Accordingly, these relays are released and contact 35 of relay IH establishes the circuit of the red lamp R of signal IS to thereby warn a westbound train of the presence of the As relays LH and U are released, the supply of energy to the transformer lM is interrupted, while contacts 39 and 40 of relay IJ cause the direct current supplied to wires 3W and ID to be of reverse polarity. This energy causes the polar contact 44 of relay SE to move to its right-hand or reverse position to establish the circuit of the yellow lamp Y of the upper portion of signal 3S, while neutral contact 45 of this relay is picked up and establishes the circuit of the primary winding of transformer 3M so that alternating current is supplied to the circuit of line wires 5W and I0. As alternating current energy is not supplied to the circuit of wires 3W and Ill, relay 3J is released and its contacts 48 and 49 cause the energy supplied to wires Hi and 5W to be of reverse polarity.

As direct current of reverse polarity together with alternating current is supplied to wires and W, the contacts of relay 5.7 are picked up, while contacts 52 and 53 of relay 5H cooperate to establish the circuit of the yellow lamp Y of the upper portion of signal 58, and its contact 54 establishes the circuit of the primary winding of the transformer 5M.

As relay 5J is picked up, its contact 60 establishes a branch circuit from the circuit of the upper yellow lamp of signal 58 to light the lower yellow lamp Y of this signal, while contacts 55 and 51 of this relay cause the direct current energy supplied to line wires l9 and l W to be of normal polarity.

Accordingly, signal 58 displays a yellow light over a yellow light, while direct current of normal polarity together with alternating current is supplied to the circuit of line wires [0 and WV that the adjacent westbound signal displays its green or clear indication.

The eastbound signals are unafiected by the presence of the train in section 6T at the west end of the stretch shown in the drawings and continue to display their green or clear indications.

When the train in section 6T advances into section 2T, track relay ZTR releases and interrupts the line circuits formed by wires SW and I0 and by wires 2E and Ill. As a result of interruption of the circuit of wires It and 2E, relays 2H and 2J release and signal 2S is caused to display its red or stop indication, while as a result of the interruption of the circuit of wires Ill and 3W, relay 3H releases and causes signal 38 to display its red instead of its yellow indication.

On release of the contacts of relay 3H its contact t5 interrupts the supply of energy to the l transformer 3M, while its contact 6| interrupts the circuit for supplying direct current to line wires it and SW when the contacts of relay 3J are released. Accordingly, the supply of energy to the line circuit formed by wires It] and SW is cut off and relays 5H and SJ release and condition signal 58 to provide its red or stop indication to thereby prevent a westbound train advancing beyond the end of the passing siding and entering the single track stretch after the eastbound train has entered this stretch.

As relay 51-1 is released, its contact interrupts the supply of energy to the transformer 5M, while as relay 5J is released, its contacts establish connections to supply direct current of reverse polarity to the circuit of line wires l0 and l W and thus cause the adjacent westbound signal in the rear to display its yellow or caution indication, while as will be understood byplacing Fig. LA at the right of Fig. 1C 'to-extend-the track stretch, when relay 1H is energized and relay U is released, direct current energy of reverse polarity only is'supplied to the circuit of line wires energized but relay 3.7 is deenergized. Under these conditions signal 38 provides its yellow or caution indication, and direct current of reverse polarity together with alternating current is supplied to the circuit of line wires l0 and SW so that signal 58 provides its approach medium indication.

From the foregoing it will be seen that as soon as an eastbound. train advances beyond the end of a passing siding, the intermediate westbound signal and the westbound signal at the leaving end of the adjacent passing siding in advance both display red or stop indications. In addition, the westbound signal at the entrance end of the passing siding in advance and the adjacent westbound signal in its rear display their yellow or caution indications so that a westbound train has ample warning of the approach of the eastbound train.

At this time as there is no westbound train in the track stretch, the eastbound signals continue to display their green or clear indications.

When the eastbound train advances into section 3T, track relay 3TH, releases and additionally interrupts the circuit of line wires 3W and Ill, and of line wires 2E and It. When this train advances into section 4T, track relay QTR releases and interrupts the circuit of line wires $13 and It) so that relays 4H and U release and cause signal 4S to display its red or stop indication. Release of the track relay 4TB also interrupts line wires l0 and 5B but as no energy is supplied to this circuit at this time interruption of the circuit is without efiect.

On release of track relay ATR its contact 63 establishes a pick-up circuit for relay 48R. This circuit also includes front contact 62 of relay 4H and is interrupted on release of the contacts of relay 4H. The relay 4H is of a type the neutral contacts of which are slow in releasing sothat they remain picked up for a short time subsequent to the release of the contacts of the track relay. During this period energy is supplied to the relay 45R so that its contacts pick up and its contact 64 establishes a stick circuit to main,- tain the relay energized as long as the track relay 4TB or the relay 51-1 is released.

When the train advances into section 5T, track relay -5TR releases and additionally interrupts the line circuits, while contact 53 of the track relay interrupts the supply of energy over the back contacts of relay EU to the line wires Ill and y [W so that the signal at the entrance of the passing siding displays its red instead of its yellow indication. At this time the adjacent signal in the rear of that signal continues to display its yellow indication.

When the train advances into section EST at When the train vacates the section 5T at the left-hand side of Fig. LA, the track relay for the section picks up to permit energy tobe supplied to the relays U and 4-H. As hereinafter ere Ill and. SW and the relay SH' is i fplained, direct current of normal polarity together with alternating current is supplied to the line wires l and I'W at this time and the r..- lays [J and IE are both energized so that signal IS displays its green or clear indication, while direct current of normal polarity together with alternating current is supplied to the circuit of line wires 3W and I0.

Accordingly, when the rear of the train vacates sections TI and 3T, relays 3H and 3J are both energized and signal 38 displays its green or clear indication, while direct current of normal polarity together with alternating current is supplied to the circuit of line wires I0 and SW so that when the rear of the train vacates sections 4T and 5T, relays 5H and EJ are both energized and the signal 58 will be conditioned to display ,its green or clear indication. In addition, on picking up of the contacts of relays 5H and 5.) direct current of normal polarity together with alternating current is supplied to the circuit of line wires IW and I0 so that the signal at the entrance end of the passing siding will display its green or clear indication.

When the train vacates section -BT at the left hand end of Fig. IA, the track relay for the section picks up to permit energy to be supplied over WiresGE and ID to govern the adjacent signal in the rear. However, at this time relay 2H is released and interrupts the supply of alternating current to the transformer 2N while contact 34 of track relay ZTR interrupts the supply of direct current to the line circuit so that energy is not supplied over this line circuit and the s nal controlled over the circuit continues to display its stop indication.

When the rear of the train vacates section 2T, track relay ZRTR picks up and its contact 34 establishes the circuit for supplying direct current of reverse polarity to the circuit of line wires 6E and ill so that the signal at the entrance end of the passing siding shown at the left-hand side of Fig. LA displays its yellow or caution indication.

When the train advances far enough to vacate section 3T, direct current of reverse polarity is supplied over wires 2E and Hi to the relay 2H so that signal 23 is conditioned to display its yellow or caution indication, while alternating current as well as direct current is supplied to the line circuit for the adjacent signal in the rear.

When the train vacates section 4T, track relay, 4TB picks up and its contact 63 interrupts one stick circuit for the relay 4SR but this relay is maintained energized by current supplied over the stick circuit which includes back contact 62 of relay 4H. Accordingly, contact 6'6 of relay ISR remains picked up and maintains the supply of direct current of reverse polarity to the line wires 2E and ID.

When the train vacates section 5T, track relay 5TB establishes the circuit of wires 4E and 10 so that direct current of reverse polarity is contact 23 establishes the circuit of the primary winding of transformer 4M so that alternatin current as well as direct current of reverse polarity is supplied to wires 2E and I0. Accordingly, relay 2J picks up and its contact 10 is closed so that the lower yellow lamp as well as the upper yellow lamp of signal 28 is lighted and the signal displays its approach medium indication. In addition, on picking up of relay 2J its contacts 32 and 33 change the polarity of the direct current supplied to the line circuit for the adjacent signal in the rear from reverse to normal with the result that that signal displays its green or clear indication.

When the train vacates section 6T at the righthand side of Fig. 10, signal 68 continues to display its stop indication as explained above, while there is no change in the aspects of the other eastbound signals.

When the train vacates the section in advance of section 6T, direct current of reverse polarity is supplied to the relay 6-H and signal 68 is conditioned to display its yellow or caution indication. At this time relay EJ remains released so that its contact l5 interrupts the circuit of the primary winding of the transformer '6M and alternating current is not supplied to the line wires 4E and i0. Accordingly, signal 4S continues to display its yellow or caution indication and there are at this time two caution indications in the rear of the train. This is desirable where the passing sidings are short, and insures that a second or following train has ample warning of the presence of the train in advance.

When the train under consideration advances beyond the intermediate signal in advance of the signal at the exit end of the passing siding shown at the right-hand side of Fig. 10, that is the signal corresponding to signal 48, direct current of reverse polarity is supplied to the line circuit for controlling signal is, and signal 28 displays its yellow or caution indication while direct current of reverse polarity together with alternating current is supplied to the line circuit for controlling signal 68. Accordingly, relays EH and EJ are both picked up and signal 66 displays its yellow over yellow or approach medium indication, while direct current of normal polarity together with alternating current is supplied to the line circuit for controlling the signal 43 and this signal therefore displays its green or clear indication.

It will be seen, therefore, that the signals are controlled in such manner that the first signal in the rear of a train displays its red or stop indication, the second signal in the rear of the train displays its yellow or caution indication, while the third and fourth signals in the rear normally display their approach medium and clear indications respectively. However, when the second signal in the rear of a train is the signal at the exit end of a passing siding, the adjacent signal in the rear, that is, the signal at the entrance end of the passing siding, displays its caution indication instead of its approach medium indication.

In addition, it will be seen that when an eastbound train is present in the portion of the track opposite a passing siding, the westbound signal directly in front of the train is at stop, while the first intermediate signal is at caution, the signal at the exit end of the next passing siding is at approach medium and the next signal in its rear is at clear. As soon as the eastbound train advances beyond the passing siding, the westbound intermediate signal and single track stretch.

The signals operate in substantially the same manner on movement of a Westbound train through the track stretch as they do for movement of an eastbound train through the stretch, and operation of the signals will not be traced in detail.

Although I have herein shown and described only one form of railway signaling system embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In a signaling system for a stretch of railway track having a pair of track rails divided by insulated joints into a plurality of successive block sections including a first, a second, a third and a fourth block section and having a first passing siding beside the first block section and a second passing siding beside the fourth block section, in combination, a signal at the entrance end of each block section and governing entrance of trains moving in one direction into the associated block section, each of said signals being capable of displaying a clear, an-

approach medium, a caution and a stop indication, a pair of conductors for each block section governed by trafiic conditions in such section, electroresponsive means for each section energized over the conductors for such section and controlling the signal for such section and also controlling the supply of energy to the conductors for the adjacent block section in the rear, the electroresponsive means for each section being effective when deenergized to condition the associated signal to provide its stop indication, when supplied with direct current of reverse polarity to condition the associated signal to display its caution indication, when supplied with direct current of reverse polarity together with alternating current to condition th associated signal to display its approach medium indication,

and when supplied with direct current of normal polarity to condition the associated signal to dis play its clear indication, the electroresponsive means for each section being effective when supplied with alternating current to supply direct current of normal polarity and when not supplied with alternating current to supply direct current of reverse polarity to the conductors for the adjacent block section in the rear, the electroresponsive means for each block section except the fourth block section being effective when supplied with direct current of either polarity to supply alternating current to the conductors for the adjacent block section in the rear, the electroresponsive means for the fourth block section being effective when supplied with direct current of either polarity together with alternating current to supply alternating current to the conductors for the third block section.

2. In a signaling system for a stretch of railway track having a pair of track rails divided by insulated joints into a plurality of successive block sections including a first, a second, a third and a fourth block section and having a first passing siding beside the first block section and a second passing siding beside the fourth block section, in combination, a signal at the entrance end of each block section and governing entrance of trains moving in one direction into the associated block section, each of said signals being capable of displaying a clear, an approach medium, a caution and a stop indi cation, a pair of conductors for each block section governed by trafiic conditions in such section, electroresponsive means for' each section energized over the conductors for such section and controlling the signal for such section and also controlling the supply of energy to the con.- ductors for the adjacent block section in the rear, the electroresponsive means for each section being effective when deenergized to condition the associated signal to provide its stop indication, when supplied with direct current of reverse polarity to condition the associated signal to display its caution indication, when supplied with direct current of reverse polarity together with alternating current to condition the associated signal to display its approach medium indication, and when supplied with direct current of normal polarity to condition the associated signal to display its clear indication, the electroresponsive means for each section being effective when supplied with alternating current to supply direct current of normal polarity and when not supplied with alternating current to supply direct current of reverse polarity to the conductors for the adjacent block section in the rear, the electroresponsive means for each block section except the fourth block section being effective when supplied with direct current of either polarity to supply alternating current to l the conductor for the adjacent block section in the rear, the electroresponsive means for the fourth block section being efiective when supplied with direct current of either polarity together with alternating current to supply alternating current to the conductors for the third block section, and means eifective when the third block section is occupied by a train moving in the reverse of said given direction to prevent the supply of direct current to the conductors for the second block section.

3. In a signaling system for a stretch of railway track having a pair of track rails divided by insulated joints into a plurality of successive block sections including a first, a second, a third and a fourth block section and having a first passing siding beside the first block section and a second passing siding beside the fourth block section, in combination, a signal at the entrance end of each block section and governing entrance of trains moving in one direction into the associated block section, each of said signals being capable of displaying a clear, an approach medium, a caution and a stop indication, a pair of conductors for each block section governed by trafiic conditions in such section, electroresponsive means for each section energized over the conductors for such section and controlling the signal for such section and also controlling the supply of energy to the conductors for the adjacent block section in the rear, the electroresponsive means for each section being effective when deenergized to condition the associated signal to provide its stop indication, when supplied with direct current of reverse polarity to condition the associated signal to display its caution indication, when supplied with direct current of reverse polarity together with alternating current to condition the associated signal to display its approach medium indication,

larity to supply alternating current to the conductors for the adjacent block section in the rear, the electroresponsive means for the fourth block section being effective when supplied with direct current of either polarity together with alternating current to supply alternating current to the conductors for the third block section, and means effective when the second block section is occupied to prevent the supply of direct our- 10 rent to the conductors for the first block section.

GEORGE E. PFLASTERER. 

